Hi ! Thank you Peter for checking the source code !
Yes I could change my sampling rate. But, well, I think it's better if pd is able work at different sampling rates, and many standards now prefer 48KHz to 44.1 (i.e. digital video recorders). For now, i'll just make a trick/abstraction that gets the working sampling rate with [samplerate~] and corrects the frequency parameter by applying a coefficient (* 44100 / SR)... However, IMHO, since frequency representation is related to the time and not the sampling rate, I think this should be corrected in the object itself, maybe as Alexandros suggested. But I don't have the skills to do that myself... hope Günther will read this. have a nice day, Raphaël 2015-05-03 5:32 GMT+02:00 Peter P. <peterpar...@fastmail.com>: > * Raphaël Ilias <phae.il...@gmail.com> [2015-05-02 16:36]: > > Hello, > > > > I was testing the [bandpass] and [notch] object's from "ggee" library, > > which compute coefficients values for vanilla's [biquad~] and discovered > > that the center frequency wasn't the one expected, but was shifted > > something like 10%. > > > > After a few measurement I found that the real center frequency was around > > 1.08841 upwards the ferquency value set to [bandpass] or to [notch] > > inlets... > > > > ...and I later realized that 48000/44100 = 1.088435... and that on my > > computer, pd is working at 48000 Hz. > > So, apparently these objects are calculating the coefficients with an > > supposed samplerate of 44100 Hz. > > You are right. I just looked at the source file for one of these > objects, and it contains a line > > x->x_rate = 44100.0; > > So apparently the sample rate for it is hard-coded. I don't know ir > Günther is actively monitoring the pd-list, but perhaps someone else > here might know how to get that code to be more responsive to different > sampling rates... > (you could change your sampling rate to 44100 in the meantime though, > Raphaël) > best, P >
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